Conventionally, in a manufacturing process of a semiconductor device, a circuit pattern is formed by performing a series of processes such as an etching process for etching an interlayer insulating film or the like formed on a substrate such as a semiconductor wafer and an asking process for removing a photoresist layer, which is used as a mask in the etching process, by oxygen plasma or CO2 plasma.
Recently, a low dielectric insulating film (so-called a Low-k film) having a lower dielectric constant than that of a conventionally used SiO2 film has been used as the interlayer insulating film. A film called a carbon-containing silicon oxide film or the like containing silicon, carbon, oxygen and hydrogen (hereinafter, referred to as a “SiCOH” film) has received recent interest for its usage as a low dielectric insulating film. As compared to the SiO2 film having a dielectric constant of about 4, the SiCOH film having a dielectric constant equal to or less than about 2.7 is a very useful film to be used as the interlayer insulating film because it has a sufficient mechanical strength. Further, a p-SiCOH film made of a porous SiCOH film may be also employed.
However, if the above-mentioned p-SiCOH film or the like is exposed to plasma in the etching process or the ashing process, it would be damaged, resulting in problems such as performance deterioration or reliability degradation because of an increase of hygroscopic property or dielectric constant. Such a damage is deemed to be inflicted because a dielectric constant is increased by removing carbon from the low dielectric insulating film and the low dielectric insulating film comes to contain moisture by absorbing water readily.
In this regard, there is known a method for recovering the damaged low dielectric insulating film by performing a silylation process for silylating the low dielectric insulating film by contacting the low dielectric insulating film with vapor of a silylating agent (for example, TMSDMA (Dimethylaminotrimethylsilane)) or the like after the etching or the ashing process (see, for example, Patent Document 1).    Patent Document 1: Japanese Patent Laid-open Publication No. 2006-49798